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Abstract

Purpose - The area of microfluidic systems has greatly enhanced the in vitro field of tissue engineering. Microfluidic systems such as microchannelled assays are now widely used for mimicking in vivo cell behaviour and studies into basic biological research. In certain cases engineered tissue cell design use 3D ordered geometrical configurations in vitro (such as microchannel assays) to reproduce native in vivo functions. The most common approach for manufacturing micro-assays is now rapid prototyping (RP) technology. The choice of assay material is dependent on the proposed cell type and ultimately the tissue application. However, many RP technologies can be unsuitable for cell growth applications because of the construction methods and materials they employ. The purpose of this paper is to describe a comparison between two different RP 3D printing methods of fabrication and investigates the merits of each technology for direct cell culture applications using micro-assays, while also examining the dispensing accuracy of both techniques.

Design/methodology/approach - Using a Thermojet and Spectrum Z510 printer pre-designed micro-assays incorporating different size microchannels are dispensed. The base materials of both methods are examined for cytotoxic effects while in solution with primary tendon fibroblasts (PFB) cells. After obtaining favorable results from the toxicology experiments, PFB cells are seeded onto the thermojet structures with a view to investigate cell adherence, encapsulation and how the channel width influences cell alignment.

Findings - This research concluded that the thermojet had a higher degree of accuracy when manufacturing structures that incorporate microchannels when compared with the Spectrum Z510. Both techniques show that the accuracy of the build decreases with reduction in channel width. The fact that the Spectrum Z510 structures have to be infiltrated with a hardening glue as a post-processing technique (since the dispensed material is water-based and hence soluble) causes a cytotoxic effect compared to the thermojet plastic which is not cytotoxic in solution with PFB cells. Seeding the PBF cells directly onto the thermoplastic structure caused problems due to the hydrophobic nature of the material and this necessitated the technique of soaking the structures in a collagen bath to penetrate the surface and reduce the interactions of hydrophobic species enhancing cell attachment and proliferation. Without this coating the thermojet structures induced strong hydrophobic interactions at the surfaces of the microchannels with the culture media resulting in non-attachment and poor cell mortality.

Originality/value - This research paper describes a comparison between the base materials and methodology of two 3D printing techniques for applications in basic biological studies. This is achieved by analysing the dispensing accuracy of both technologies and the interaction between cells and surface at the interface.